Arms out, leg cocked: as England’s Chloe Kelly took her penalty against Nigeria the forward was, she later said, confident of scoring. She not only won the game for the Lionesses, she set the record for the fastest shot in the Women’s World Cup so far.
According to data from the official match ball, the shot on Monday reached 110.79km/h (69mph) – a speed that beats the most powerful strike of the 2022-23 Premier League campaign, by West Ham’s Saïd Benrahma, that clocked in at 107.2km/h (66.6mph).
“Chloe’s penalty was just quite remarkable,” said Dr Ken Bray, of the University of Bath. “It was a very, very powerful hit.”
Dr Alexandra Atack, an associate professor of biomechanics at St Mary’s University, Twickenham, said multiple factors contribute to the power of a kick.
“The speed of the ball is determined by the speed of the kicking foot when it makes contact with the ball and how efficient the foot-ball collision is in transferring the energy,” she said.
Among the factors affecting foot speed were the motion of the hip and knee joints of the kicking leg, the speed and angle of the kicker’s approach, the motion of the stance leg, and rotation of the upper body, Atack said.
“The amount of energy these actions can generate and how they are coordinated will influence the kicking foot speed towards the ball,” she said, adding that the efficiency of the foot-ball collision was down to which part of the foot made contact with the ball, and the rigidity of the ankle during the impact.
“The harder the collision, the faster the ball speed afterwards.”
Bray said that while there were optimum places to aim for in the goal , in particular, the top right- or left-hand corners, the speed of the ball mattered.
“You’ve got to get the ball moving at a certain rate, because what you want to do is beat the goalie’s reaction time,” he said.
Simple penalty-taking tips included approaching the ball at a 45-degree angle, and bringing the heel of the kicking leg close to the bottom before striking, but Atack said that at the top level of football a penalty kick was a whole-body action.
“Body size, shape, and [a player’s] physical characteristics [such as their strength and power capacities] can influence how an individual is best able to generate the required energy,” she said.
Individual techniques also mattered.
“When taking a penalty kick, David Beckham approached the ball from a wide angle and leant a long way over to the stance leg-side during the kicking action,” said Atack. “In contrast, Cristiano Ronaldo took a much straighter approach and remained more upright throughout the kicking action.”
What’s more, the technique used will depend on where the kick is being taken from on the pitch and whether, for example, a curved trajectory is needed.
Prof Mark Lake, of Liverpool John Moores University, noted that Kelly had a slightly “bouncing” approach to the penalty – involving a hop technique.
“The raised left foot at the start does not have much to do with the power of the kick but rather to initiate the practised rhythm of the action and to ensure an accurate foot-ball contact for max power,” he said, adding that Kelly enhanced her foot velocity by the substantial lean of her standing leg, allowing her more rotational swing on her kicking leg.
“Then she has good rotational follow-through of the kicking leg after ball contact. This technique mimics the actions of male players who also have strong kicking performance,” he said.
Bray said that, although it was not clear from video footage, Kelly’s right foot may have been pointing slightly towards the left when she kicked the ball – an unconventional position that “would have imparted some topspin which would help to keep the ball down when it was hit with such power”.
Atack added that while it was impossible to fully understand how Kelly produced such a fast kick without performing a full-body biomechanical analysis, the footballer’s confidence may also have mattered.
“It is likely that she approached the ball with real intent and therefore, could use the energy generated as she approached the ball quickly to achieve a faster kicking foot and therefore, ball speed,” Atack said.
